Cosmological consequences of exponential gravity in Palatini formalism

We investigate cosmological consequences of a class of exponential f (R) gravity in the Palatini formalism. By using the current largest type la Supernova sample along with determinations of the cosmic expansion at intermediary and high-z we impose tight constraints on the model parameters. Differently from other f (R) models, we find solutions of transient acceleration, in which the large-scale modification of gravity will drive the Universe to a new decelerated era in the future. We also show that a viable cosmological history with the usual matter-dominated era followed by an accelerating phase is predicted for some intervals of model parameters. (C) 2011 Elsevier B.V. All rights reserved.